Technical Field
The present disclosure relates to a control apparatus that suppresses the magnetization bias of a transformer.
Description of the Related Art
Conventionally, a power conversion apparatus in which a primary circuit and a secondary circuit are connected through a transformer is known. According to the above-mentioned power conversion apparatus, magnetization bias may occur on the transformer in which magnetic flux is biased. The magnetization bias of the transformer can be predicted using an amount of deviation in the excitation current which produces the magnetic flux in the transformer.
In this respect, Japanese Patent Application Laid-Open Publication Number 2016-192889 discloses a power conversion system in which a current detection device is provided in the secondary coil of the transformer to detect current flowing therethrough and the detected current is smoothed by a filter circuit. Then, an amount of magnetization bias representing an amount of deviation of the excitation current is predicted based on the smoothed current.
In the case where an amount of the magnetization bias is predicted by using the current detection device as disclosed in the above-described patent literature, the current detected by the current detection device may include offset errors. Hence, the offset error may lower the accuracy of the prediction of the magnetization bias. The offset error is defined as an amount of the detection value detected by the current detection device which is shifted within a specified value from an amount of the current actually flowing through the object to be detected. When the prediction accuracy of the magnetization bias is lowered, the magnetization bias of the transformer is unlikely to be corrected appropriately.